JP2023536098A - Process for removing fluoroorganic compounds from aqueous media - Google Patents

Abstract

The present disclosure provides a process for removing a fluoroorganic acidic compound from a solution comprising at least one protic solvent, comprising: at least one fluoroorganic acidic compound containing less than 15 carbon atoms and a protic solvent. forming a mixture of a solution containing a solvent and an extraction composition containing at least one trialkylamine and an organic solvent, the solution having a pH of 4; reacting a fluoroorganic acidic compound with the trialkylamine; forming a hydrophobic ionic compound comprising an anion of a fluoroorganic acidic compound and a cation of a trialkylamine; A step of separating into a first phase comprising a fluoroorganic acidic compound present in a solution of the organic solvent and a second phase comprising an organic solvent and a hydrophobic ionic compound; removing the second phase from the first phase and repeating the aforementioned steps at least twice, the first phase obtained in the last step being used as the initial solution; Provide processes, including:

Description

The present disclosure relates to a sequential multistage process for removing fluoroorganic compounds from aqueous media by extraction with alkylamines in organic solvents.

Fluorinated compositions are used in a wide variety of applications including waterproofing materials, electrical and oil/oil fire extinguishing foams, semiconductor etching, and fluorochemicals for lubricants; and fluoropolymers for hoses, gaskets, seals, coatings, and films. has been used for its purposes. The reasons for such widespread use of fluorinated compositions include their favorable physical properties, including chemical inertness, low coefficient of friction, low polarizability (i.e., fluorophilicity), and high temperature stability. is mentioned.

After manufacture of the fluorinated composition, the fluorinated compound, including, for example, starting materials and reaction by-products, may be removed from the waste stream produced by manufacture. Removal of the fluorinated compound may be to recover expensive starting materials and/or to avoid unwanted release of the fluorinated compound into the environment.

Processes for removing or recovering fluorinated compounds include ion exchange, ultrafiltration, distillation, liquid-liquid extraction, reverse osmosis, and adsorption onto clay, carbon, and other media. Such processes are disclosed in U.S. Patent Application Publication Nos. 2006/0205828 (Maurer et al.), 2007/0025902 (Hintzer et al.), and 2010/0084343 (Mader et al.), and U.S. Patent No. 3,882. 153 (Seki et al.), 4,369,266 (Kuhls et al.), 6,642,415 (Fuhrer et al.), 7,279,522 (Dadalas et al.), and 5,603,812 (Hommeltoft). It is known that these processes can be associated with varying degrees of deficiencies such as low efficiency, high investment costs, or increased environmental load. Another more recent effort involved the removal of fluoroorganic acids from aqueous media using alkylammonium compounds. However, it remains desirable in the art to provide efficient and environmentally friendly methods for removing fluoro-organic compounds, especially for large-scale or industrial operations.

The present disclosure provides a process for removing fluoroorganic acidic compounds from a solution comprising at least one protic solvent, comprising the steps of:
(i)
a. a solution comprising at least one fluoroorganic acidic compound containing less than 15 carbon atoms and at least one protic solvent, the solution having a pH value of up to 4;
b. forming a mixture with an extraction composition comprising at least one trialkylamine and at least one organic solvent;
(ii) reacting a fluoroorganic acid compound with a trialkylamine to form a hydrophobic ionic compound comprising an anion of the fluoroorganic acid compound and a cation of the trialkylamine;
(iii) forming a mixture, in a first phase, of at least one protic solvent and up to 50% by weight of the total amount of at least one fluoroorganic compound originally present in solution in step (i); and a second phase, the second phase comprising at least one organic solvent and a hydrophobic ionic compound;
(iv) removing the second phase from the first phase; and (v) repeating steps (i)-(iv) at least twice, wherein the first the phase is used as a solution in step (i).

Before describing any embodiments of the present disclosure in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and arrangement of components set forth in the following description. should. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. As used herein, the terms “a,” “an,” and “the” are used interchangeably and mean one or more, and “and/or” describes one or both A and/or B is used to indicate that some instances may occur, eg, A and/or B includes (A and B) and (A or B). Further herein, the recitation of ranges by endpoints includes all numbers subsumed within that range (eg, 1 to 10, 1.4, 1.9, 2.33, 5.75, 9 .98, etc.). Further herein, reference to "at least 1" includes all numbers greater than or equal to 1 (eg, at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.) . Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Unlike the use of "consisting," which is intended to be restrictive, "including," "containing," "comprising," or "having." , and variations thereof are intended to be non-limiting and are intended to encompass the items listed after them as well as any additional items. However, the use of "comprising" herein also encompasses the term "consisting of", i.e. "consisting of" in the sense of "consisting only of" Note that the use of "consisting of" is not excluded from this disclosure itself.

Amounts of components of the composition may be indicated by weight percent (or “%wt” or “wt-%”) unless otherwise specified. All component amounts are 100% by weight unless otherwise specified. When component amounts are specified by mol %, all component amounts are 100 mol % unless otherwise specified.

All preferred ranges and embodiments may be freely combined unless explicitly indicated.

The parameters described herein can be determined as detailed in the experimental section.

The present disclosure provides a process for removing fluoroorganic acidic compounds from a solution comprising at least one protic solvent, comprising the steps of:
(i)
a. a solution comprising at least one fluoroorganic acidic compound containing less than 15 carbon atoms and at least one protic solvent, the solution having a pH value of up to 4;
b. forming a mixture with an extraction composition comprising at least one trialkylamine and at least one organic solvent;
(ii) reacting a fluoroorganic acid compound with a trialkylamine to form a hydrophobic ionic compound comprising an anion of the fluoroorganic acid compound and a cation of the trialkylamine;
(iii) forming a mixture, in a first phase, of at least one protic solvent and up to 50% by weight of the total amount of at least one fluoroorganic acidic compound initially present in solution in step (i); and a second phase, the second phase comprising at least one organic solvent and a hydrophobic ionic compound;
(iv) removing the second phase from the first phase; and (v) repeating steps (i)-(iv) at least twice, wherein the first phase is used as a solution in step (i).

The process according to the present disclosure makes efficient removal of fluoroorganic acidic compounds from solutions in protic solvents feasible. The process according to the present disclosure is particularly advantageous for removing fluorinated acidic compounds from alcoholic and/or aqueous solvents or solvent mixtures in large scale or continuous multi-step processes. This is very advantageous for treating large volumes of sewage as required during large-scale industrial production or at laboratory sites. In this regard, the fluoroorganic acid compound is believed to react with at least one trialkylamine to form a hydrophobic ionic compound comprising the fluoroorganic acid anion and the trialkylammonium. This hydrophobic ionic compound then readily migrates from the protic solvent of the first solution to the organic solvent of the second solution. Thus, when the first (protic) phase is separated from the (organic) second phase, the effective removal of the major portion of the fluoroorganic acidic compounds originally present in solution a is achieved by the process according to the present disclosure. achieved. This means that an extraction composition b comprising at least one trialkylamine and at least one organic solvent is used for the extraction.

Thus, in step (i) of the process according to the present disclosure, a mixture of solution a and extraction composition b is formed. The step of forming the mixture comprises providing a solution a and an extraction composition b, contacting both a and b with each other, and mixing to form a mixture of the two liquid components. , stirring, agitating, or other steps known to those skilled in the art.

In step (ii) a reaction takes place between the trialkylamine and the fluoroorganic acid compound to form a hydrophobic ionic compound. In this regard, "reacting" includes "allowing to react", which means when the reaction occurs automatically upon contact of both components. .

Further, in step (iii) of the process according to the present disclosure, the mixture comprises at least one protic solvent and up to 50% by weight of the total amount of the fluoroorganic acidic compound initially present in solution a in step (i). separated into a first phase containing Preferably, the fluoroorganic acidic compound is reduced by at least 20% in the first extraction stage compared to the initial concentration. Given the hydrophobicity of the ionic compound formed in step (ii) and the generally desirable certain immiscibility of the at least one protic solvent with the at least one organic solvent, the mixing described herein Separation of the mixture in two phases as described herein can readily occur once is stopped. This may involve transferring the mixture described herein to another container or compartment. Generally, as is known in the art, the phase separation into two phases described herein may already be visible, even when examined with the naked eye. However, determination and confirmation of phase separation may also be performed by means well established in the art. Preferably, a portion of the total amount of at least one fluoroorganic compound described herein is at least 60% by weight of the total amount of fluoroorganic acidic compounds initially present in the first solution in step (i); Preferably at least 65 wt%, more preferably at least 70 wt%. A major portion as described herein, based on the total amount of fluoroorganic acidic compound initially present in the first solution in step (i), such as at least 80% by weight, or even at least 90% by weight, It can be even more.

Removal of the second phase from the first phase in step (iv) can then be carried out by any common means known to those skilled in the art. Preferably, means and methods are chosen which are suitable for continuous and/or large scale operation. Steps (i)-(iv) are repeated at least twice and the first phase obtained in step (iv) is used again as solution a in step (i). In this regard, the process can be carried out again with a first solution consisting essentially of the first phase obtained in step (iv). It is also possible to add the first phase to another fresh portion of the first solution a. This may be the case when performing the processes described herein in a continuous large-scale mode of operation. Therefore, more complete removal of fluoroorganic acidic compounds can be achieved.

Since wastewaters containing fluoro-organic compounds are often produced continuously during production in the chemical industry, the purification of these compounds from these by-product-containing wastewaters continuously, rather than batchwise. is highly desirable. Also, the process according to the present disclosure is well suited for continuous mode operation. Therefore, the processes described herein are preferably carried out in continuous mode. Preferably, this comprises continuous feeding of a solution comprising at least one fluoroorganic acidic compound (a) and/or extraction composition (b) in step (i), continuous reaction between the fluoroorganic acidic compounds in step (ii) , continuous separation in step (iii) and/or continuous removal of the second phase from the first phase in step (iv). Such a continuous mode of operation also preferably includes each of the process steps described herein in different vessels and/or compartments to which the product of the previous production step is transferred, e.g., by respective piping. means to be implemented. It is also preferred in that the process described herein is carried out in continuous mode, wherein the second phase continuously extracts the first phase in a multistage continuous process.

The term "protic solvent" has its commonly used meaning in the art and refers to any solvent molecule capable of donating at least one proton to another molecule. represent. Protic solvents are generally known to those skilled in the art and may be selected either according to the immediate needs of the process and the solubility of the fluoroorganic acidic compound. However, it is also possible that the protic solvent is already part of the wastewater or even constitutes the main part of the wastewater and is therefore not an option. Preferably, the at least one first protic solvent is selected from water, at least one alcohol, at least one acid, and any combinations and mixtures thereof. This has the advantage that a good phase separation between the first and second phases in step (iii) of the process according to the present disclosure can be obtained, which generally follows in step (iv ) and/or the time it takes to complete step (iii) is highly desirable. In this regard, the at least one alcohol is preferably selected from methanol, ethanol, propanol, butanol, pentanol, hexanol and any combinations and mixtures thereof. The acid can be selected from organic acids such _as formic acid and acetic acid, and from inorganic acids such as HF, _H3PO4 , _{H2SO4 ,} HCl, or _HNO3 . In this regard, solutions or dilutions of these acids in water are preferably used in the processes described herein. The water content of such acid-containing phases can be, for example, less than 99.9 wt%, less than 99 wt%, or even less than 98 wt%, based on the total weight of the first phase. On the other hand, the alcohol content can be up to 99%, up to 95%, or up to 90% by weight, based on the total weight of the first phase. The water content may be very low, for example lower than 70%, or lower than 60%, or even lower than 25% by weight based on the total weight of the first phase. Therefore, it is possible to extract fluorinated acids from highly concentrated acids using the method according to the present disclosure. The pH value of the first phase may be up to 3.5, preferably up to 3, more preferably up to 2.

The at least one fluoroorganic acidic compound can be selected from aliphatic linear, branched or cyclic fluorinated acidic compounds. In this regard, the fluorinated acid may be selected from fluorinated acids comprising a carbon backbone of at least 2 carbon atoms, preferably of at least 3 carbon atoms, for example of at least 5 carbon atoms; The chain optionally contains at least one oxygen atom. The fluorinated acid may be selected from those containing a carbon backbone of 25 carbon atoms or less, preferably 20 carbon atoms or less, more preferably 15 carbon atoms or less. It is particularly preferred that the fluorinated acid is selected from those containing a carbon backbone of 2 to 15 carbon atoms, preferably 3 to 14 carbon atoms, more preferably 2 to 10 carbon atoms. . The at least one fluorinated acidic compound may comprise at least one carboxylic acid moiety, at least one sulfonic acid moiety, at least one sulfate moiety, and/or at least one alcohol moiety. As known to those skilled in the art, fluorinated alcohols are acidic and fall within the definition of fluorinated acidic compounds used herein, and thus can be advantageously removed by processes according to the present disclosure. Fluorinated acids are carboxylic acids (R _f —COOH), sulfonic acids (R _f —SO ₃ H), sulfates R _f —CH ₂ —O—SO ₃ ⁻ ), or alcohols (R _f —CH ₂ OH), Including dicarboxylic acid (HOOC--R _f --COOH), disulfuric acid (HO ₃ S--R _f --SO ₃ H).

ＣＦ_３－Ｏ－（ＣＦ_２）_３－Ｏ－ＣＦＨ－ＣＦ_２ＣＯＯＨ、ＣＦ_３－Ｏ－（ＣＦ_２）_２ＣＯＯＨである。 Acids/alcohols can be fully fluorinated or partially fluorinated. Examples are e.g. _CF3COOH , _CF2HCOOH , _C2F5COOH , _{C2F4H -} COOH, _{C4F9 -} COOH _{, C7F15COOH} , _{CF3- O-} ( _CF2 ) ₃ -O- _CF2COOH ,

CF ₃ —O—(CF ₂ ) ₃ —O—CFH—CF ₂ COOH, CF ₃ —O—(CF ₂ ) ₂ COOH.

Fluorinated acids can also have 1 to 4 hydrogens and/or chlorines in the molecule. Further examples are the commercially available compounds known by the names OPA and ADONA (ammonium 4,8-dioxy-3H-perfluorononanoate).

In particular, some fluoroorganic compounds described herein are known as PFCAs (perfluorinated carboxylic acids). Thus, removal of currently commercially available fluoro-organic compounds becomes feasible with the process according to the present disclosure. Fluoroorganic acidic compounds in this regard are fluorinated or perfluorinated C2-C20 carboxylic acids. Typically, the fluoroorganic acidic compound is present in the first solution in an amount from 0.4 ppb to 30,000 ppm. Surprisingly, using the present invention, fluorinated acidic compounds can be extracted with high selectivity from hydrogen-containing analogues from aqueous phases (see Examples).

Regarding the at least one alkylamine used in the process according to the present disclosure, the at least one alkylamine is selected from tertiary alkylamines, preferably from higher boiling trialkylamines, i.e. trialkylamines with a high boiling point. may The at least one trialkylamine comprises a straight or branched chain alkyl group, the alkyl group having at least 4 carbon atoms, preferably at least 5 carbon atoms, more preferably at least 6 carbon atoms. including. The at least one trialkylamine may contain a linear or branched alkyl group containing up to 40 carbon atoms, preferably a total of up to 35 carbon atoms, more preferably up to 30 carbon atoms. good. Accordingly, at least one alkylamine is a straight or branched chain alkyl group containing 15 to 40 carbon atoms, preferably 15 to 35 carbon atoms, more preferably 18 to 19 carbon atoms. preferably included. For example, the at least one trialkylamine is preferably a tertiary amine, ie, a trialkylamine, with a total of all carbon atoms in the range of 18-29. Achieving particularly efficient removal of fluoroorganic acidic compounds from the first solution described herein using at least one alkylamine having carbon atoms in the preferred ranges described herein. can be done.

Amines of the present disclosure may be liquid and should have a boiling point below 450° C. at room temperature. In one embodiment, amines useful in this disclosure are less than 20 mg, 10 mg, 5 mg, 3 mg, 2 mg, 1 mg, 0.75 mg, 0.5 mg, or even less than 0.25 mg per 100 mL measured at ambient conditions. can be described as a water-insoluble amine with a water solubility of

Preferably, the at least one alkylamine is an amine of formula (I):
NR ₁ R ₂ R ₃ (I)
[In the formula, R ₁ , R ₂ and R ₃ may be the same or different, and at least one of R ₁ , R ₂ and R ₃ is linear or branched , a saturated or unsaturated carbon group, which may optionally contain a heteroatom. Preferably any one of R ₁ , R ₂ and R ₃ contains at least 4 carbon atoms, preferably at least 5 carbon atoms, more preferably at least 6 carbon atoms. For example, the number of carbons in R ₁ -R ₃ can vary including, for example, carbon backbones containing at least 5, 6, 7, 8, 10, 12, or even 14 carbon atoms. Preferably, the at least one alkylamine used herein is trihexylamine, trioctylamine, tridecylamine, tridocecylamine, alamine, triisooctylamine, trioctyl-decylamine, N- selected from methyl-dioctylamine, N,N-dimethyloctylamine, tributylamine, octylamine, dioctylamine, and any combinations and mixtures thereof. Advantageous high purity tertiary amines for use in the process according to the present disclosure are available, for example, from Cognis, Monheim, Germany under the trade names: "ALAMINE 300" (tri-n-octylamine), "ALAMINE 308" (tri-n-octylamine). -isoctylamine), "ALAMINE 336" (tri( _C8 / _C10 )amine), "ALAMINE 310" (tri-isodecylamine), and "ALAMINE 304" (tri-laurylamine). Tertiary trialkylamines are advantageous over primary and secondary amines because they can undergo unwanted side reactions with fluorinated acids, for example by forming amides.

The temperature of the mixture, ie, the aqueous emulsion after addition of the at least one alkylamine, can be controlled to advantageously enhance the removal of fluoroorganic compounds in the processes described herein. In this regard, it is preferred that the process is carried out at a temperature below 80°C, preferably below 70°C, more preferably below 60°C. Preferably, the process is carried out at a temperature in the range of 3°C to 80°C, preferably 5°C to 70°C, more preferably 10°C to 60°C, even more preferably 15°C to 50°C. In particular, the processes described herein can be carried out at room temperature and general ambient conditions. This is very advantageous for carrying out the process on an industrial scale, as neither cooling nor heating is required, which helps conserve energy, equipment and resources, making the process described herein making it highly advantageous from both an economic and environmental point of view.

Generally, at least one alkylamine is present in at least one organic solvent. This has the advantage that the extraction of the at least one fluoroorganic compound can be accelerated. In this regard, it is preferred that at least one organic solvent is not miscible with water. This has the advantage that a clear separation between the aqueous and organic phases can be obtained. Generally, the at least one organic solvent is less than 500 ppm at a temperature of 20° C. according to the method "Prufmethoden-Verordnung (EG) Nr. 440/2008, Teil A, Method A.6 (Test according to OECD-Pruefrichtlinie 105) , more preferably less than 50 ppm in water. Furthermore, at least one organic solvent exhibits a boiling point of at least 50°C, preferably at least 70°C, more preferably at least 100°C. The use of organic solvents that exhibit boiling points above the aforementioned temperatures at ambient pressure, i.e., high-boiling organic solvents, greatly increases the risk of the solvent evaporating or even boiling at the preferred temperatures of the processes described herein. It has the advantage of improved inherent process safety in that it is reduced. Preferably, the at least one organic solvent is selected from linear hydrocarbons, cyclic hydrocarbons, ethers, aromatic solvents, and any combinations and mixtures thereof. For example, toluene (boiling point 111° C.), mesitylene (boiling point 165° C.) or octane (boiling point 125° C.) may be used. In this regard, higher boiling points are preferred, ie mesitylene is preferred over octane. As an alternative to or in addition to the aforementioned solvents, it is preferred to use fluorinated solvents such as HFE's Novec-Fluids (available from 3M). Such solvents preferably include perfluorinated trialkylamines (NR ₃ ) and/or fluorinated ethers (eg methoxyperfluorobutene HFE 7100). Preferably, the boiling point of the fluorinated solvent is above 50°C. Non-fluorinated solvents should not have reactive functional groups such as esters, ketones, OH-groups, since they can react with the fluorinated acid b. Further, it is preferred that the volume ratio of solvent to amine is between 1:1 and 1000:1. In this regard it is also preferred that the molar ratio of amine to fluorinated acid/alcohol is at least 1:1 to 1000:1, preferably 1:2 to 100:1. These solvents may also be halogenated, such as chlorinated or fluorinated, which is advantageous for extracting fluorinated or perfluorinated compounds in the process according to the present disclosure. . In this regard, the at least one organic solvent is preferably selected from toluene, xylene, mesitylene, octane, or gasoline, and any combinations and mixtures thereof or halogenated derivatives thereof.

Furthermore, it has been found that even better extraction results can be obtained when non-fluorinated polar organic co-solvents are used in combination with the aforementioned solvents. Preferably, the compounds are used as non-fluorinated polar organic solvents, which can also be characterized as surfactants. Therefore, it is preferred that at least one non-fluorinated surfactant is used in addition to the solvents described herein. Surfactants as used herein contain a polar portion and a non-polar portion. For example, polar moieties may include heterocycles such as amides or pyrrolidinones, and non-polar moieties may be linear or branched alkyl groups. The hydrophilic-lipophilic balance of these compounds described herein can be estimated by their HLB values, commonly determined by the Griffin method, below.
HLB=20 ^* M(H)/M
M(H) is the molecular weight of the hydrophilic portion of the molecule.
M is the molecular weight of the whole molecule.

For use herein, the at least one non-fluorinated surfactant preferably exhibits an HLB value of 5 or less, preferably 4 or less, more preferably 3 or less. A commercially available example of at least one non-fluorinated surfactant is the "Surfadone" compound manufactured by Ashland Specialty Corp, eg, "Surfadone LP-300". The at least one non-fluorinated surfactant, based on the total weight of the extraction composition b, in an amount of 0.1-60% by weight, preferably 0.15-50% by weight, more preferably 0.2- It is preferably contained in the extraction composition b in an amount of 10% by weight.

A second solution and a first solution comprising at least one trialkylamine in step (i) of the process described herein, preferably in at least one organic solvent described herein. Contacting with can be carried out by adding the second solution to the first solution. After addition, it is preferred to stir the resulting mixture for at least a sufficient time to contact the at least one alkylamine with the fluoroorganic compound present in the first solution. As a general rule, however, the contact time between the at least one alkylamine, ie the second solution, and the first solution is preferably greater than 0.1 seconds in some devices, but generally 5, 4 , 3, or even less than 2 hours. Exemplary devices that can be used for agitation include: vortexers, agitators, sonicators, and other such devices known in the art.

Without wishing to be bound by theory, extraction of fluoroorganic acidic compounds, particularly acids, from a first solution in a protic solvent with an alkylamine as described herein yields an ion pair hydrophobic organic liquid. It is believed to be accomplished using a fluoroorganic acid and an alkylamine to form. It is then separated from the protic solvent of the first solution, allowing subsequent further extraction and processing. This separation is further enhanced when using at least one organic solvent in the second solution described herein when the first solution contacts at least one alkylamine in the process according to the present disclosure. be done. Because of this immiscibility, the first phase (ie, protic phase) and second phase (ie, organic or aprotic phase) generally separate after stirring has ceased. However, if the mixture is biphasic but does not phase separate by itself, means known in the art, including centrifugation, can be used to facilitate phase separation. Separation of the first phase from the second phase in step (iv) of the processes described herein can be performed by any suitable means known in the art. Surprisingly, the process according to the present disclosure allows fluorinated acids to be separated from other non-fluorinated acids (eg, _CH3COOH vs. _CF3COOH ). Accordingly, solution a in the process described herein may further comprise at least one inorganic acid, preferably selected from sulfuric acid, hydrochloric acid, acetic acid, nitric acid, and any combinations and mixtures thereof.

A process according to the present disclosure is preferably carried out in continuous mode. This is very advantageous, for example, for industrial scale applications where continuous treatment of wastewater is required. Preferably, the processes described herein are carried out in an extraction column, preferably a sequential multi-stage extraction column. In this regard, multistage extraction columns known in the art preferably comprise at least two stages. Preferably, the process is carried out in Scheibel columns, centrifugal extractors (eg from Robatel) and other means known to those skilled in the art. Such devices are described in Chem. Ing. Tech. 2020, 92, No. 12, 1941-1952.

It has further been found that the process according to the present disclosure gives the best results when performed at certain pH values. In particular, it was found that the best results were obtained at low pH values, medium pH values showed mediocre results, and high pH values could not achieve effective removal of fluoro-organic compounds. Do you get it. Carrying out the processes described herein at a preferred pH value includes adjusting the pH value of first solution (a) prior to contacting first solution (a) with at least one alkylamine. can be easily achieved by Therefore, it is preferred to adjust the pH value of the first solution to a pH value of max 4, preferably max 3, more preferably max 2 before contacting with the at least one alkylamine in step (i). Also, this regeneration process is preferably carried out as a continuous multi-step process.

Recollecting and, where practicable, recycling materials and compounds used in processes in order to carry out processes in the chemical industry in an economically efficient manner and to meet environmentally friendly requirements. Or it is desired in the technical field to reuse. In the process according to the invention, it is desirable to at least recollect at least one alkylamine used in the process. It has been found that this can be achieved by adding at least one base to the organic phase after carrying out the aforementioned process steps. Therefore, the process according to the present disclosure preferably comprises an additional step (vi) of adding at least one base to the organic phase to regenerate the at least one trialkylamine and/or solvent. Performing this additional step has the advantage that at least one trialkylamine is recovered from its protonated form and/or solvent and can be recollected and/or recycled to the processes described herein. have. Therefore, step (vi) is preferably carried out continuously. More preferably, the regenerated at least one trialkylamine is recycled for use in step (i) of the process described herein. Addition of the base and recollection of the regenerated alkylamine can be accomplished by conventional means known to those skilled in the art. Regarding bases, it is preferred that at least one base is selected from KOH, _NH4OH , NaOH, and any combinations and mixtures thereof. These bases provide favorable results, are readily soluble in aqueous media, and are commercially available in any given amount at a reasonable price. The pH of the basic aqueous regeneration solution for the organic phase may be above 8, preferably above 9, more preferably above 10.

Regeneration of the organic phase (meaning a clean, reusable extraction system) to recover the trialkylamine and solvent is preferably done via multistage and continuous mode. By doing this, the clean extraction mixture can be fed directly into the aqueous phase for extraction of the fluoroorganic acidic compounds. Thus, a closed loop system is provided for the extraction of fluorinated acidic compounds from solutions, particularly aqueous solutions such as wastewater streams.

The extracted aqueous phase (first phase) may contain traces of trialkylamine and/or solvent. Within the present process, it may be an option to remove such impurities by treating the extracted aqueous phase with adsorbents such as silica, activated carbon, alumina, molecular sieves, and the like. This treatment can be carried out batchwise or continuously, for example by using a column packed with adsorbent and passing the aqueous phase through it, or the adsorbent can be put directly into the aqueous phase and after some time It can be filtered off.

The fluorinated acidic compounds that can be obtained in high concentrations after carrying out the methods described herein can be further processed, for example to recover usable materials such as emulsifiers, or For example, it can be destroyed by incineration or oxidation.

The process according to the present disclosure is preferably a continuous multi-step process for extracting fluoroorganic acidic compounds from a solvent stream, preferably a wastewater stream. The water stream is preferably selected from an industrial sewage stream or a water stream from a vessel containing a solvent phase containing at least one fluoroorganic acid compound.

The present disclosure will be further described without wishing to limit the disclosure thereto. The following examples are presented to illustrate certain embodiments, but are not intended to be limiting in any way. Before that, some test methods used to characterize the materials and their properties are described. All parts and percentages are by weight unless otherwise indicated.

Test method NMR analysis method:
All FT-NMR spectra were acquired at about 25° C. on Bruker AVANCE NEO 600 MHz and Bruker AVANCE III HD 600 MHz NMR spectrometers equipped with a 5 mm SmartProbe and a 5 mm TCI Cryoprobe, respectively. ¹⁹ F-NMR spectra were obtained for samples of selected low-level FC components using a TCI cryprobe.

(1) Aqueous phase sample:
For each sample, an aliquot of the fluid was accurately weighed into a 5 mm outer diameter glass NMR tube, spiked with a small, accurately weighed amount of 2,2,2-trifluoroethanol internal standard, and used for NMR analysis. Diluted with a small amount of heavy water ( _D2O ). 600 MHz ¹ H-NMR and 565 MHz ¹⁹ F-NMR spectra were acquired. In all cases, trifluoroethanol was used as an internal standard to allow calculation of absolute weight percent concentrations of sample components without the need to identify and quantify all of the other components in the samples.

(2) Organic phase sample:
For each sample, an aliquot of the fluid was accurately weighed into a 5 mm outer diameter glass NMR tube and spiked with a small, accurately weighed amount of 1,4-bis(trifluoromethyl)benzene (p-HFX) internal standard. and diluted with a small amount of deuterated acetonitrile (CD ₃ CN) for NMR analysis. 600 MHz ¹ H-NMR and 565 MHz ¹⁹ F-NMR spectra were acquired. In all cases, p-HFX was used as an internal standard to allow calculation of absolute weight percent concentrations of sample components without the need to identify and quantify all of the other components in the sample.

Gas Chromatography Analysis 1 mL of aqueous sample and 0.6 mL of BF ₃ /MeOH complex solution (20%, from Merck) were filled into 10 mL headspace vials and partially closed. After shaking, the vials are heated to 70° C. for 30 minutes using the autosampler unit of the Headspace GC instrument and then analyzed by Headspace-GC-FID using external calibration.

Instrument: Agilent 6890N
Column: Rtx-200, trifluoropropylmethylpolysiloxane, 0.32 mm x 105 m, 1.5 µm
Injection volume: 1500 μL
Temperature: 50°C (5 minutes) - 5°C/min -> 200°C
Flow rate: 3.5 mL/min

Liquid Chromatography Mass Spectrometry (LC-MS):
Submitted samples were dissolved in methanol prior to analysis. A standard solution was prepared from an aqueous solution of Adona determined by NMR to have a concentration of 28.36%.

Instrument: Agilent 6470 Triple Quad LCMS MAID 1665
Column: Zorbax Bonus RP, 4.6 x 75 mm, 3.5 μm
Solvent A: water containing 6 mM ammonium acetate Solvent B: methanol containing 6 mM ammonium acetate Gradient: 75% B to 100% B in 4 minutes Injection volume: 2 μL
Column temperature: 40°C
Flow rate: 0.5 mL/min MS: negative electrospray

Materials used:

Example 1
Aqueous mixtures containing different fluoroorganic acidic compounds were extracted with a mixture of 0.5% by weight of alamine in mesitylene with different pH values of the aqueous phase. Extractions were performed at 20° C. in a single stage to demonstrate the different effects of pH.

The concentrations of fluoroorganic acid compounds before and after extraction were determined by NMR.

Example 2 (comparative example):
A 250 mL plastic bottle was filled with 200 mL of an aqueous solution containing 328 ppm trifluoroacetic acid (TFA) and 38 ppm pentafluoropropionic acid. After adjusting the pH value of the aqueous solution to the target value (pH 3) with sulfuric acid, the extractant solution (1 g Alamine 336 dissolved in 19 g mesitylene) was added. After sealing the bottle, the resulting mixture was vigorously shaken for 1 minute. After shaking the solution at 20° C., the aqueous phase was separated from the extractant solution by filling the mixture into a separatory funnel for phase separation. NMR of the aqueous phase revealed a significant reduction of TFA to 27 ppm and pentafluoropropionic acid to <1 ppm during a single extraction stage.

Example 3:
The extraction described in Example 2 was repeated four times with the same aqueous solution as in Example 2 with the following procedure (four-stage extraction). After each extraction step (first extraction, procedure similar to Example 2), the aqueous phase was separated from the extractant (1 g alamine in 19 g mesitylene) and filled into new 250 mL plastic bottles. Fresh extractant solution (1 g alamine in 19 g mesitylene) was then added, the mixture shaken and again the aqueous phase separated. By repeating this procedure three times, the aqueous solution was purified in four steps (extraction steps). NMR on the aqueous solution after four extraction steps revealed a dramatic reduction in TFA to 0.3 ppm and pentafluoropropionic acid to <1 ppm.

Example 4:
Aqueous solutions containing TFA, pentafluoropropionic acid and tetrafluoropropionic acid were treated as described in Example 3 (four-stage batch extraction). Experiments demonstrate the advantages of multi-stage extraction and solvent differences (mesitylene vs. octane). The results are listed below:

Example 5
A 4-stage centrifugal extractor LX-204 manufactured by Rousselet Robatel (France) was used to purify water streams with different fluorinated species listed in the table below.

Parameters: phase ratio of alamine (5%) to water in mesitylene = 0.1 w/w;
Flow rate: 4.1 kg/min aqueous phase, 0.41 kg/min organic phase; RPM = 3300; RT;
pH of aqueous phase: 1.7.

Regeneration of Organic Phase The collected organic phase was treated with a 20 wt % KOH solution at 20° C. in the same apparatus LX-204.

Parameters: phase ratio of organic/aqueous KOH = 20 w/w.
Flow rate: 0.09 kg/min aqueous KOH phase, 1.82 kg/min organic phase, RPM 3000.
Results: All fluorinated species in the organic phase were below detection limits (<1 ppm). The organic alamine/mesitylene phase can be reused for further extractions.

Example 6
The aqueous stream containing TFA was treated with 4 consecutive stages of extraction (trioctylamine/mesitylene) and the organic phase was also regenerated using 4 consecutive stages (18 wt% NaOH).

Particles in the wastewater were first filtered with a 1 μm filter. After adjusting the pH to 1-2.0 with concentrated sulfuric acid (96 wt%), 100 kg/h of wastewater containing 93 ppm of C2 was added to 10.8 kg/h of organic solvent amine) to remove the acid in the extraction (1. Centrifugal extractor from Robatel, 4 stages). After extraction, the TFA content was <3 ppm ( ^* detection limit).

The TFA-retained organic phase is regenerated by extraction with an aqueous sodium hydroxide solution (18% by weight) in a regeneration step (2. centrifugal extractor, 3 stages) to purify the wastewater (1. centrifugal extractor). returned to

Liquid-liquid extraction (mass balance)
1. Centrifugation 2 . Centrifugation First Centrifugation:
100 l/h of wastewater containing heavy phase and 10 kg/h of mesitylene/alamine extractant containing light phase are removed, 100 l/h of clarified extract water phase and 10 kg/h of mesitylene/alamine and fluoroorganic acid and a retained light phase containing a mixture of compounds. These 10 kg/h of retained light phase were introduced into a second centrifuge and regenerated with 1 kg/h of NaOH, whereby 10 kg/h of regenerated light phase mesitylene/alamine mixture and all 1 kg/h of heavy phase containing fluoroorganic acid compounds is obtained. 10 kg/h of regenerated light phase is returned to the extraction process in Centrifuge 1.

This demonstrates the benefits of continuous multi-stage extraction of contaminated water streams, including continuous multi-stage regeneration to recover the trialkylamine/solvent and establish a closed loop.

Example 7
An aqueous mixture containing 3 wt% _CF3COOH , 65 wt% acetic acid, 10 wt% HF, 2.5 wt% _HNO3 was prepared in Example 3, except that the aramine/ _CF3COOH ratio was varied. Aramin/mesitylene extraction as described in . For sample 2, the original 3 wt% CF ₃ COOH solution was diluted 1:1 with deionized water.

Example 8
105 g of an aqueous mixture containing 8.3 wt % TFA, 65 wt % CH ₃ COOH, 9 wt % HF and 3 wt % HNO ₃ was mixed with 105 g containing 35 g trioctylamine and 70 g mesitylene. The extraction mixture was used for extraction with vigorous stirring. After phase separation, NMR measurements gave the following results.

The results from Examples 7 and 8 demonstrate the highly selective removal of TFA relative to _CH3COOH from aqueous mixtures, further demonstrating that fluorinated acids can be extracted from highly acidic media and low water content. to demonstrate.

Example 9
A flask (250 mL) equipped with a magnetic stir bar was placed at room temperature with aqueous HCl (30% w/w; 200 g) containing trifluoroacetic acid (237 μg). The solution was then extracted with a mixture of trioctylamine and mesitylene (1 g trioctylamine + 19 g mesitylene). After phase separation, the lower phase was extracted again. The extraction process was similar to that previously described. After corresponding phase separation, the lower phase was passed through a silica gel (0.1 wt%) column from the bottom to the top. Results are summarized in Table 8.

Example 10
To demonstrate the effect of non-fluorinated surfactants in the first extraction step of the method described herein, different species were prepared in plastic bottles adjusted to pH=1.7 using sulfuric acid. 100 g of an aqueous mixture containing fluoroorganic acid compounds of . Then 10 g of mesitylene, 5 g of LP-300, and 0.5 g of alamine were added to the bottle, after which the bottle was closed and shaken vigorously for 1 minute. After standing for 30 minutes, two liquid phases appeared in the bottle. A small sample was taken from the bottom aqueous phase of the bottle and analyzed for fluorochemical content by NMR analysis.

The above procedure was followed except that LP-300 was not used. The results of Example 10 and Comparative Example 2 are summarized in Table 7.

Claims (17)

A process for removing fluoroorganic acidic compounds from a solution comprising at least one protic solvent comprising the steps of:
(i)
a. a solution comprising at least one fluoroorganic acidic compound containing less than 15 carbon atoms and at least one protic solvent, the solution having a pH value of up to 4;
b. forming a mixture with an extraction composition comprising at least one trialkylamine and at least one organic solvent;
(ii) reacting the fluoroorganic acidic compound with the trialkylamine to form a hydrophobic ionic compound comprising an anion of the fluoroorganic acidic compound and a cation of the trialkylamine;
(iii) forming said mixture, in a first phase, said at least one protic solvent and up to 50% by weight of the total amount of said at least one fluoro, which was initially present in said solution in step (i); separating into a first phase comprising an organic acidic compound and a second phase comprising said at least one organic solvent and said hydrophobic ionic compound;
(iv) removing said second phase from said first phase; and (v) repeating steps (i)-(iv) at least twice, said wherein a first phase is used as said solution in step (i);
process, including 2. The process of claim 1, wherein said process is carried out in a continuous mode of operation. 3. A process according to claim 1 or claim 2, wherein said process is carried out in a continuous mode of operation, said second phase continuously extracting said first phase in a multi-stage continuous process. 4. The method of any one of claims 1-3, wherein the at least one first protic solvent is selected from water, at least one alcohol, at least one acid, and any combinations and mixtures thereof. process. Process according to any one of the preceding claims, wherein the pH value of said first phase is up to 3.5, preferably up to 3, more preferably up to 2. Said at least one fluoroorganic acidic compound is selected from aliphatic linear, branched or cyclic fluorinated acidic compounds, preferably said at least one fluorinated acidic compound comprises at least one carboxylic acid moiety, A process according to any preceding claim, comprising at least one sulfonic acid moiety, at least one sulfate moiety and/or at least one alcohol moiety. Said at least one alkylamine is selected from tertiary alkylamines, preferably said at least one trialkylamine has at least 5 carbon atoms, preferably at least 6 carbon atoms, more preferably at least 7 A process according to any one of claims 1 to 6, comprising a straight or branched chain alkyl group containing 1 carbon atom. The at least one trialkylamine is an amine of formula (I):
NR ₁ R ₂ R ₃ (I)
[wherein R ₁ , R ₂ and R ₃ may be the same or different, and at least one of R ₁ , R ₂ and R ₃ may optionally contain a heteroatom; The process according to any one of claims 1 to 7, wherein the amine is a linear or branched, saturated or unsaturated carbon group. A major portion of the total amount of said at least one fluoroorganic acidic compound is at least 60% by weight, preferably at least 65% by weight, more preferably at least 65% by weight of the total amount of fluoroorganic acidic compounds initially present in said solution a in step (i) is at least 70% by weight. Process according to any one of the preceding claims, wherein said at least one organic solvent has a solubility in water at 20°C of less than 0.1%, preferably less than 500 ppm, more preferably less than 50 ppm. 11. Any one of claims 1 to 10, wherein said extraction composition b further comprises at least one non-fluorinated surfactant having an HLB value of preferably 5 or less, preferably 4 or less, more preferably 3 or less. process described in . Process according to any one of the preceding claims, wherein solution a further comprises at least one inorganic acid, preferably selected from sulfuric acid, hydrochloric acid, acetic acid, nitric acid, and any combinations and mixtures thereof. A process according to any one of claims 1 to 12, wherein said process is carried out in an extraction column, preferably a multi-stage extraction column, a Scheibel column, a centrifugal extractor and any combination thereof. A process according to any one of claims 1 to 13, wherein said process comprises an additional step (vi) of adding at least one base to said organic phase to regenerate said at least one alkylamine. . 15. The process of claim 14, wherein step (vi) is performed continuously and/or as a multi-step process. 16. The process of Claim 14 or Claim 15, wherein the regenerated at least one alkylamine is recycled for use in step (i). A process according to any one of the preceding claims, wherein said process is a continuous process for extracting fluorinated compounds from a solvent stream, preferably a water stream.